Commit 192301e7 authored Nov 13, 2013 by Oleg Nesterov Committed by Ingo Molnar Nov 27, 2013

sched: Check TASK_DEAD rather than EXIT_DEAD in schedule_debug()



schedule_debug() ignores in_atomic() if prev->exit_state != 0.
This is not what we want, ->exit_state is set by exit_notify()
but we should complain until the task does the last schedule()
in TASK_DEAD.

See also 7407251a "PF_DEAD cleanup", I think this ancient
commit explains why schedule() had to rely on ->exit_state,
until that commit exit_notify() disabled preemption and set
PF_DEAD which was used to detect the exiting task.

Signed-off-by: Oleg Nesterov <oleg@redhat.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: David Laight <David.Laight@ACULAB.COM>
Cc: Geert Uytterhoeven <geert@linux-m68k.org>
Cc: Tejun Heo <tj@kernel.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: Linus Torvalds <torvalds@linux-foundation.org>
Link: http://lkml.kernel.org/r/20131113154538.GB15810@redhat.com


Signed-off-by: Ingo Molnar <mingo@kernel.org>

parent 86506a99

kernel/sched/core.c

+3 −3

Original line number	Diff line number	Diff line
		@@ -2414,10 +2414,10 @@ static inline void schedule_debug(struct task_struct *prev)
		{
		/*
		* Test if we are atomic. Since do_exit() needs to call into
		* schedule() atomically, we ignore that path for now.
		* Otherwise, whine if we are scheduling when we should not be.
		* schedule() atomically, we ignore that path. Otherwise whine
		* if we are scheduling when we should not.
		*/
		if (unlikely(in_atomic_preempt_off() && !prev->exit_state))
		if (unlikely(in_atomic_preempt_off() && prev->state != TASK_DEAD))
		__schedule_bug(prev);
		rcu_sleep_check();

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